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United States Patent |
5,102,369
|
Martin
,   et al.
|
April 7, 1992
|
Dark meat deboner
Abstract
The tibula, fibia and femur of a whole poultry leg are removed by making a
lengthwise cut along the inside of the leg, along the rear of the tibula
and femur, then making a lateral cut part way through the knee joint, then
supporting the thigh and bending the knee joint to expose the end of the
femur, then plunging a cup-type knife over the exposed end of the femur
and through the knee joint, to sever the ligaments in the joint and
separate the exposed end of the femur from the thigh flesh, then moving
the knife laterally of the femur axis to withdraw the femur through the
lengthwise cut in the thigh, and then removing the tibula and fibia
through the lengthwise cut in the drumstick. An apparatus for
automatically performing a portion of the method is also disclosed.
Inventors:
|
Martin; Eugene (Denver, PA);
Cook; Scott (Strasburg, PA)
|
Assignee:
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Foodcraft Holdings, Inc. (Wilmington, DE)
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Appl. No.:
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690822 |
Filed:
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April 26, 1991 |
Current U.S. Class: |
452/135; 452/136 |
Intern'l Class: |
A22C 021/00; A22C 017/00 |
Field of Search: |
452/135,136,138
|
References Cited
U.S. Patent Documents
4644608 | Feb., 1987 | Martin et al. | 452/136.
|
4669150 | Jun., 1987 | Nanmoto et al. | 452/136.
|
4736492 | Apr., 1988 | Hazenbroek et al. | 452/138.
|
4811457 | Mar., 1989 | Lindert | 452/136.
|
4843682 | Jul., 1989 | Bowen | 452/136.
|
4993113 | Feb., 1991 | Hazenbroek | 452/136.
|
Primary Examiner: Little; Willis
Attorney, Agent or Firm: Shoemaker and Mattare, Ltd.
Claims
I claim:
1. A method for removing the femur from a whole poultry leg, without
separating the drumstick from the thigh, comprising steps of making a
lengthwise cut along the inside of the leg, over substantially its entire
length, down to and along the rear of the tibula and femur, then making a
lateral cut part way through the knee joint, then cutting through the knee
joint, and withdrawing the femur through the lengthwise out in the thigh,
and then removing the tibula and fibia through the lengthwise cut in the
drumstick.
2. A method for removing the femur from a whole poultry leg, without
separating the drumstick from the thigh, comprising steps of making a
lengthwise cut along the inside of the leg, over substantially its entire
length, down to an along the rear of the tibula and femur, then making a
lateral cut part way through the knee joint, then supporting the thigh and
bending the knee joint in its natural direction until the femur and tibula
are at an acute angle to expose the knee joint, then plunging a cup-type
knife over the exposed end of the femur and through the knee joint, to
sever the ligaments in the joint and separate the exposed end of the femur
from the thigh flesh, then, without fully withdrawing the knife, moving it
laterally of the femur axis to withdraw the femur through the lengthwise
cut in the thigh, and then removing the tibula and fibia through the
lengthwise cut in the drumstick.
3. An apparatus for removing the bones from a poultry leg which has been
prepared by making a lengthwise cut along the inside of the leg, along the
femur and tibula, and a transverse cut through only the inside of the knee
joint, comprising
means for holding the drumstick portion of the leg by the hock,
means for gripping the thigh of the leg and flexing the leg, to expose the
knee joint and the knee end of the femur,
a semicylindrical knife and means for plunging the knife substantially
along its axis over the exposed end of the femur, to sever the knee joint,
and
means for moving the knife laterally of the femur axis, without withdrawing
it from the femur, so as to pull the femur through the lengthwise cut.
4. The invention of claim 3, further comprising a conveyor for moving the
leg along a predetermined path in a predetermined orientation, and wherein
the hock holding means is affixed to the conveyor.
5. The invention of claim 4, wherein the hock holding means comprises a
pair of spaced tabs, each having a slot therein through which the hock
cannot pass.
6. The invention of claim 3, wherein the knife is mounted on an arm having
a pivot support, and the knife moving means comprises a link for
oscillating the arm with respect to the pivot, a first cam for driving the
arm cyclically, and means for laterally moving the pivot support in
synchronization with the first cam.
7. The invention of claim 6, wherein the moving means comprises a
crankshaft driven at the same speed as the first cam, and a pittman arm
extending between the crankshaft and the pivot support.
8. The invention of claim 3, wherein the thigh gripping means comprises an
anvil formed of two opposed resilient members with a slot therebetween
through which the femur can pass, and a cradle for clamping the thigh
against the anvil.
9. The invention of claim 8, further comprising a second cam for operating
the thigh anvil, and means for rotating said second cam in unison with
said first cam.
10. The invention of claim 8, further comprising a third cam for operating
the thigh cradle, and means for rotating said third cam in unison with
said first cam.
Description
BACKGROUND OF THE INVENTION
This invention relates to the art of butchering, and more particularly to
an apparatus for automatically removing the bones from whole poultry
(especially chicken) legs.
There are numerous prior devices for removing bones from drumsticks, and
some for deboning thighs. However, we are unaware of any prior device or
method which debones whole legs, without separating the drumstick from the
thigh.
Recently developed deboning machines have focused particularly on the
breast, and the market has demonstrated high consumer acceptance of
deboned breasts. The value of a breast can be significantly enhanced by
removing the bones prior to sale. It now appears that a similar market
exists, or would exist, for deboned whole chicken legs. The present
invention addresses the problem of removing bones from whole legs, which
present problems different from, and in some respects more difficult than,
breasts.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of this invention to remove
entirely the bones from a whole chicken leg, without severing the
drumstick from the thigh, and without any substantial removal of flesh. A
related object is to produce a boned leg product which is attractive and
cleanly cut, and free of tendons and ligaments.
Another object is to automate the tediously repetitive operation of boning
legs in a poultry processing plant.
It should be understood that, although refer to chicken legs throughout
this document, the method and apparatus disclosed would be easily adapted
to other birds, or even other animals generally, and that the invention
claimed is intended to cover all such uses.
The above objects are met by an apparatus comprising a frame and a leg
conveyor thereon, the conveyor having means for engaging the hock of the
leg (the large joint at the bottom of the drumstick, the feet having
previously been removed), whereby the conveyor moves a series of legs
through a deboning station.
The apparatus performs part of a method for deboning whole legs, which is
part of the invention as well. The method comprises making a lengthwise
cut along the inside of the leg, over substantially its entire length,
down to and along the rear of the tibula and femur, then making a lateral
cut part way through the knee joint, then supporting the thigh and bending
the knee joint in its natural direction until the femur and tibula are at
an acute angle to expose the knee joint, then plunging a cup-type knife
over the exposed end of the femur and through the knee joint, to sever the
ligaments in the joint and separate the exposed end of the femur from the
thigh flesh, then, without fully withdrawing the knife, moving it
laterally of the femur axis to withdraw the femur through the lengthwise
cut in the thigh, and then removing the tibula and fibia through the
lengthwise cut in the drumstick.
Common terminology (such as "hock", "drumstick", and "knee") is used
throughout this specification, instead of corresponding proper anatomical
terms, for the benefit of the ordinary reader.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings,
FIG. 1 is a top plan view of an apparatus embodying the invention;
FIG. 2 is a front elevation of a portion thereof;
FIG. 3 is a sectional view taken along the transverse plane 3--3 in FIG. 1;
FIG. 4 is an enlarged view of a portion of FIG. 3;
FIG. 5 is a sectional view taken along the plane 5--5 in FIG. 2;
FIG. 6 is a sectional view taken along the plane 6--6 in FIG. 2;
FIG. 7 is a an enlarged side elevation of a plunge knife shown in FIG. 3;
and
FIG. 8 is a view of the plunge knife, taken in direction "A" in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An apparatus embodying the invention comprises a frame 10, shown generally
in FIG. 1, which supports a linear, horizontal chain conveyor passing
along a vertical center plane P from an upstream end to a downstream end,
as indicated by the arrow. The conveyor is driven intermittently by a
conventional mechanism, not shown, including an electric motor and a
right-angle gear reduction unit.
At the upstream end of the apparatus, there is a joint preparation station
20, where preliminary cutting steps are presently performed manually. It
may be possible to automate the cutting steps, which are described in
detail below with the operation of the apparatus.
The joint preparation station comprises horizontal surfaces 22 on either
side of the chain conveyor, where workers can orient and partially cut
whole chicken legs. The broken lines toward the top of the Figure are
intended to indicate that there is corresponding structure on either side
of the center plane, and in fact the entire apparatus is substantially
symmetrical. To avoid duplication, only structure on one side of the
center plane is shown in detail.
"Whole chicken leg" herein means the thigh and drumstick, connected at the
knee joint, without the feet, which have previously been removed, so that
the drumstick terminates at the hock, which is the end corresponding to
the ankle joint. A leg is illustrated in FIGS. 5 and 6. As best seen in
those figures, and in FIG. 2, the conveyor 12 comprises a single No. 60
(3/4 inch pitch) chain 24 riding on a UHMW plastic guide 26, and provided,
on either side, with pairs of tabs 28, 30 at seven-and-a-half inch
intervals.
Each tab pair has a space 32 therebetween, and a transverse slot 34 sized
to receive the distal end of a drumstick, but too narrow for the hock to
pass through. The slot is cut at a compound angle, so that the center of
the slot extends, in a direction away from the center plane, preferably
40.degree. rearward (i.e., in the upstream direction) and 30.degree.
downward, to properly orient the drumstick for the deboning operation.
Just downstream of the joint preparation station, the drumstick is engaged
from below by a channel member 36 extending parallel to the conveyor
direction, just below and outside the bottom of the tab slots, and from
above by two stationary rods extending generally in the direction of the
conveyor. The inboard of these rods, 38, slightly closer to the center
plane than the innermost tabs, keeps the hock within the slots. The
outboard rod 40 descends in the downstream direction, and curls partially
around the channel iron, so that as the leg progresses downstream, the
knee is flexed and the thigh is partially inverted, with the longitudinal
cut in the thigh facing down and away from the conveyor.
The femur removing station occupies the center portion of FIG. 1, in which
structure on only one side of the center plane is shown. It may be
mentioned here that the conveyor chain moves intermittently, stroking
thirty inches per cycle. Since the tab spacing is a quarter of this
distance, four legs are advanced per stoke, and the four are acted upon
simultaneously during the dwell period in the femur removing station.
Details of the femur removing station are shown in the top and lateral view
of FIGS. 1 and 3, from which unessential detail has been omitted. The
mechanism shown comprises three large cams 42, 44, 46, the outer two of
which are identical and drive the plunge knives described below; the
middle cam 44 drives a thigh clamp. The cams are mounted on a common shaft
48 which extends parallel to, and is driven through gearing (not shown)
by, a crankshaft 50 having a Pittman arm 52 with a small stroke, that
controls the position of the pivot point 54 of the knife arm 56. Although
the crankshaft movement is continuous, the conveyor movement is
synchronized with it, mechanically or electrically, at one cycle per
crankshaft revolution, and the cams have dwell events in which the knife
is retracted, during movement of the conveyor. The lowermost cam 58 (FIG.
3) operates a thigh clamp 60 which immobilizes the femur and properly
positions it for the plunge knife. Structural members 74, 76, 78 are
stationary, being connected to the frame 10.
The thigh clamp 60 includes an anvil 62 comprising a metal support and two
stiff but deflectable polyethylene members 64 (or "squeegees") which are
connected to the support at their outer edges only. The squeegees meet, or
nearly meet, edge-to-edge opposite a dwell position of one of the conveyor
tab slots and astride a transverse plane containing the centerline of the
plunge knife, defining between them a slit or slot through which the femur
can be drawn, but not the entire thigh. The squeegees (see FIG. 8) are
stiff enough to provide a substantial supporting force for the thigh, but
sufficiently resilient to allow the slot to open slightly as the femur is
drawn through.
The thigh is clamped against the squeegee surface from above by a "cradle"
66, which is drawn from an upper rest position toward the squeegees by the
link 68 driven by cam 58. The anvil itself is moved by the cam 44 via a
follower on link 70, and lever 72, between a lower rest position and an
upper working position. Thus, the pocket formed between the squeegees and
the cradle is open at rest (while the conveyor is moving), and closed
around the thigh during deboning.
FIGS. 7 shows the plunge knife 80 in detail, viewed along direction "A" in
FIG. 3. The mounting hole by which the knife is connected to its arm is
shown at the left side of the drawing; the cutting edge 82 is depicted at
the right. The upper surface of the knife, adjacent the cutting edge,
defines a cylindrical arc. The upper edge is beveled at 45.degree., and,
as indicated by the broken line, the cutting edge forms a circular arc.
The oval opening 84 at the center of FIG. 8 provides clearance for the end
of the femur.
The lower end of the knife arm is pivotally connected to the link 86
suspended from the lever 72, and also to the pittman, which varies the
location of the pivot point during the cycle. As will be explained, the
movement and orientation of the knife is critical to the deboning process.
The upper end of the knife arm is oscillated with respect to the pivot
point by the link 88, which is driven by cam 42 or 46 via a follower that
is constrained to move within a slot 90 in the stationary member 76. It
should be noted that the four knives operate in unison, each pair of the
knives being driven by a respective one of the cams. Also, the four
squeegee supports, and the cradles are ganged together, or are unitary,
and operate together.
FIG. 4 shows successive positions of the knife, which are produced by the
cooperative effect of the cams 42, 44, 46, 58, and links 52, 70, 72, 86,
88. The degree markings denote cam positions, 0.degree. being the middle
of the dwell event. The sequence is described below with the operation of
the device.
Downstream of the femur removing station, the conveyor chain passes through
a final station for nicking the tibula, to weaken it, and then breaking
the tibula. This station is shown in FIGS. 2, 5 and 6. As shown in FIGS. 2
and 5, the conveyor 12 carries the leg by its hock beneath a pivotally
supported knife 92, which is biased downward by a spring 94. Thereafter,
the drumstick is engaged from above by a stationary breaking bar 96, which
descends in the downstream direction. An inboard bar 98 keeps the hock in
the slot.
In operation, workers at the upstream end of the apparatus receive
quantities of whole legs at the joint preparation station. Each leg is
delivered to the appropriate side of the apparatus; the legs cannot be
loaded indiscriminately. Actually, looking in the downstream direction
from the preparation station, the right legs of the bird are processed by
the left side of the machine, and vice-versa. Each leg is placed on the
work surface of the preparation station with the hock toward the center
plane and the inside of the leg up, that is, with the knee rearward. Now,
an incision or cut is made through the flesh on the inside of the leg,
from the hock to the hip, along the downstream side of the tibula and
femur. The leg is not cut through, but just deep enough to pass along the
bone. Next, a lateral cut is made into the knee joint on the exposed
(inner) side of the leg.
The leg, now ready for automatic processing, is now loaded into the next
available conveyor tab slot. When the conveyor is cycled, the leg is
passed to one of the four identical sites at the deboning station, after
the knee has been flexed by the bar 40. During the dwell period of the
conveyor, with the hock still firmly within the tab slots, the following
events occur in rapid succession: First, the squeegee support is moved
upward and toward the conveyor by the cam 44, further opening the knee
joint, which is still held together by the ligaments at the outside of the
knee. Nearly simultaneously, the cradle is driven toward the squeegee,
compressing the thigh so as to immobilize the femur. The plunge knife now
moves downward, substantially along both the axis of the femur and that of
the knife, roughly direction "A" in FIG. 3, so that the cutting edge of
the knife passes between the femur and the tibula, severing the remaining
uncut ligaments, and also separating the end of the femur from the
surrounding thigh meat.
The knife now undergoes a particularly critical motion, illustrated in FIG.
4. It is withdrawn somewhat in the direction it entered, but only
partially--to a point at which the cutting edge is still adjacent the
femur. Next, owing to the lateral shifting of the location of the pivot
point of the knife arm, in conjunction with the movement of the knife
driving link, the knife moves substantially perpendicular to the femur
axis, that is, in direction "B" (FIG. 3), and thereafter a substantial
distance approximately vertically downward, as shown. Since the femur has
been freed already at its knee end, and because the lengthwise cut
previously made is now on the bottom of the thigh, the femur can pass out
of the thigh meat, through the slot between the squeegees, which prevent
the thigh meat from following.
As it happens, the femur usually remains loosely connected to the thigh by
some flesh near the hip, but it can be easily removed later by hand or
otherwise. FIG. 2 illustrates the femur dangling from the thigh,
downstream of the deboning station. By following the arrow in FIG. 2, one
can see that the thigh first passes under the knife, which nicks the
tibula near the hock (FIG. 5), providing a locus for breaking when the leg
is forced downward by the breaking bar (FIG. 6). It is then a simple
matter to remove the hock, to withdraw the tibula and fibia through the
lengthwise cut, and to sever and tissues remaining connected to the femur,
without damaging the product. A unitary boned whole leg results.
Inasmuch as the invention is subject to modifications and variations, it is
intended that the foregoing description and the accompanying drawings
shall be interpreted as illustrative of only one form of the invention,
whose scope is to be measured by the following claims.
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